Edge-On CT Detectors With Time-Offset Depth Sampling
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Solution Overview
Problem
Computed Tomography (CT) systems face challenges in achieving sufficient angular sampling frequency, leading to artifacts, aliasing, and impaired spatial resolution due to limitations in detector electronics and material properties, particularly with low-Z materials.
Innovation Solution
Implementing a time offset measurement scheme between measurement periods of edge-on detector elements at different depths, allowing for overlapping measurement periods to increase angular sampling frequency without introducing noise penalties, thus enabling higher gantry rotation speeds and reducing the need for data filtering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional CT systems use large detector elements (e.g., 0.7 mm) to reduce cost and complexity, then device complexity and manufacturing cost decrease, but manufacturing precision and measurement precision of small structures deteriorate
Solution Approach 1:
The detector array is divided into multiple independently controllable depth segments (e.g., first depth segment and second depth segment). Each segment can be selectively activated based on the imaging depth requirements, allowing the system to use only the necessary detector elements for each scan, thereby reducing effective complexity while maintaining high precision where needed.
Solution Approach 2:
The system dynamically adjusts which depth segments are active based on the imaging task. For superficial structures, only the first depth segment is used; for deeper structures, the second depth segment is activated. This dynamic configuration allows the system to optimize between complexity and precision for different imaging scenarios.
2Adaptability or versatility
If the system images both superficial and deep structures using the same detector configuration, then versatility is improved, but measurement precision for superficial structures deteriorates due to deep structure attenuation
Solution Approach 1:
The detector array is segmented into depth-specific groups (first depth segment for superficial structures, second depth segment for deep structures). This segmentation allows the system to select the appropriate detector segment based on imaging depth, preventing deep structure attenuation from degrading superficial structure imaging quality.
Solution Approach 2:
Different depth segments are optimized for different imaging depths. The first depth segment detectors are positioned and configured for optimal superficial structure detection, while the second depth segment detectors are optimized for deep structure imaging. This local optimization ensures high measurement precision for both superficial and deep structures without compromise.
3Manufacturing precision
If multiple detector arrays at different depths are always active to improve measurement precision, then manufacturing precision and measurement precision improve, but device complexity and energy consumption increase
Solution Approach 1:
The system dynamically activates only the necessary depth segments based on imaging requirements. For superficial structures, only the first depth segment is active; for deep structures, the second depth segment is activated. This dynamic approach maintains high precision capabilities while reducing effective device complexity and energy consumption for each specific imaging task.
4Productivity
If all detector elements are activated simultaneously to improve productivity, then productivity increases, but energy consumption and difficulty of detecting and measuring increase due to signal overlap
Solution Approach 1:
The detector array is segmented into depth-specific groups that are activated selectively. For superficial structures, only the first depth segment detectors are activated; for deep structures, only the second depth segment detectors are activated. This segmentation eliminates signal overlap between different depth ranges, making signal detection and measurement straightforward while maintaining high imaging throughput.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enhances angular sampling frequency, reduces aliasing, and improves spatial resolution, allowing for faster image acquisition while maintaining data quality and preventing artifacts.
Implementation Method 1
a plurality of X-ray photons are passed through an object... each detected photon indicating a respective attenuation along a respective path through the object
Data Source
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AI summary
Disclosed is a measurement method performed by a Computed Tomography, CT, system (10). The CT system (10) comprises an x-ray source and an x-ray detector array of photon counting edge-on detectors, wherein each edge-on detector has a number of depth-segments, also referred to as detector elements (15), arranged at different spatial locations in the direction of incoming x-rays. The method comprises to apply a time offset measurement scheme that provides a time offset between measurement periods for at least two different detector elements (15) located at different depths, wherein the time offset is chosen so that at least two measurement periods at least partially overlaps in time. Disclosed is also a corresponding CT system (10), a control unit (20) for a CT system and a measurement circuit (30) for a CT system (10). A computer program controlling a CT system (10) is also disclosed. The disclosed technology provides for a higher sampling frequency in the angular direction.